Operation of gas wells



LApril 20, 1937. G. E. VAN vooRHls OPERATION OF GAS WELLS Filed April 7.1936 INVENTOR Patented Apr. 20, 1937 UNITED STATES PATENT OFFICE 1Claim.

My invention relates to natural gas-wells, and consists in an improvedmethod of operating such wells. This application is a continuation inpart of application Serial No. 756,773, led by me on or about the 10thday of December, 1934.

The usual practice in gas-fields is to drill from the earths surfacedownward to the first gasyielding sand. A tubular casing is theninstalled in the subterranean bore, and connection is made at the earthssurface to a tank or pipe line for removal of the gas paid by the sandinto such casing.

When in the operation of the well, the yield of this first sand becomeslow, the bore is drilled deeper-down to the next lower or secondgassand. Within the casing already installed a line of tubing is rundown to this second sand, and the yield of the well then comprises thegas delivered by the second sand into the tubing, plus the yield of therst sand into the region between the tubing and the casing. When theyield of the second sand becomes low, the well is drilled to the thirdgas-sand, and the line of inner tubin'g is lowered into communicationtherewith. 'I'he gas yielded by the third sand is conducted through theinner tubing to the top of the well, and the gas yielded by both thefirst sand and the second is conducted upward in the region between thetubing and the casing. In such manner a gas-well is progressivelydrilled from one gas-yielding stratum to another, and two or more strataare held in communication with the outlet of the well.

Years ago, when the natural gas fields were rst opened, it was foundthat gas-sands were naturally dry, or included oil in such smallquantities as to be liobjectionable. While gas is usually present inoil-bearing sands, it is to be understood that there is a cleardistinction in the art between a gas-sand and an oil-sand. A gas-well,properly considered, operates on gasbearing strata and an oil-welloperates primarily on oil-bearing strata. With these generaldistinctions in mind, it will be understood that my invention relates tothe operation of gas-wells.

As above mentioned, with the gas fields of the country were rst opened,the gas-sands were found to be substantially free of water, this beingparticularly true in the case of the eastern elds of the United States.And no great difficulty was experienced in operating gas-wells in themanner described. Today, however, conditions are different.

Dueto carelessness, ignorance, and laxity of law, operators did not plugexhausted and aban- (Cl. 16S- 21) doned wells, and over a period ofyears water from the earths surface and from subterranean water sandsand other water-bearing strata has Y been allowed to drain into suchwells, with the consequence and effect that now most gas-sands in theeastern fields carry water.

Before considering the invention in detail, I shall describe a knownmethod of operating a gaswell in which only the rst and second gas-sandshave been tapped. The water in the gas-yielding strata seeps into thebore of the well, and in relatively short time oods the bottom of thewell to a level above the second sand, thereby throttling the yield ofsuch sand. When this occurs the normal operation of the well isintermitted, and the water is removed in known way by means of a bailer,lowered through the inner line of tubing. The bailing operation is slow,and during the operation substantial quantities of gas are lost. at themouth of the well. When the water has been bailed out, the well isrestored to normal operation.

The seepage of water from the gas-sands and other water-bearing stratacontinues and soon oods the second sand again. The bailing operationmust be and is repeated, and in many cases the expense and lossesoccasioned by the frequent bailing operations turn economic success tofailure. For this reason many elds in which gas still exists have beenabandoned.

I am aware of another known method which has been proposed for removingliquid from wells. but so far as I know it has never proved adequate insolving the problem of seepage in gas-wells. Such method consists incementing the lower end of a line of tubing in communication with thelower gas-sand, in such manner that the water seeping from the uppersand is collected in the bore of the well above the body of cement andexternally of the line of tubing. Thus, only the relatively slightseepage from the lower stratum drains to the bottom of the well, wherebythe intervals between floodings and the periods between bailingoperations are greatly increased. The relatively large seepage from theupper sand (and from other water-yielding strata above) collects in thewell above the body of cement at the base of the tubing and sooner orlater rises to such level that the upper sand is flooded. In order toremove such water, a ported coupling is included in the inner line oftubing, opposite to or at the base of said upper sand, and from time totime the ports of the coupling are opened, permitting the watercollecting in the well above or opposite to the upper sand to drainintothe inner tubing, whence it may be bailed out,`or blown to the topof the Well by the gas streaming at high velocity upward through thetubing from the lower gasyielding sand. It is characteristic ofthis pro-5 posed practice that the upper sand is never completely drained; it isnormally flooded to greater or less degree, and the gas yielded by thesand must bubble through the liquid and rise. Of course, in new elds inwhich gas is delivered l under high pressure, an adequate yieldsometimes may be obtained from a iiooded or partially iiooded gas-sand,but in a well in which the upper sand yields gas under relatively lowpressure this method is unsuitable. And even in high l pressure wellsthe ooding of the yielding sands holds the delivery far below what itmight otherwise be. 1 If the lower portion of a sand stratum isinundated, even if only for a relatively short time, it will be readilyunderstood that water, 20 due to capillary attraction, will be drawn upinto the body of sand above the water, and will operate to constrict thegas-delivering ways and passages between the grains of sand. Inaccordance with my invention I provide a method of operat- 25 ing agas-well, whereby the entire upper gasyielding stratum (or strata) ismaintained substantially dry. Thus I obtain maximum yield in anygas-well having two or more paying sands in operation, and in particularI make it feasible 30 to operate gas-wells in fields which hitherto havebeen abandoned.

In the accompanying drawing, Fig. I is a diagrammatic, sectionalview ofa gas-well prepared for operation in accordance with the invention;

35 Fig. II is a view in section and to larger scale of a particularcoupling employed in the well; and Fig. III is a sectional view to stilllarger scale of a coupling of modified and preferred form.

In exemplary way a gas-well W is shown. It

40 is shown to be drilled to the second gas-sand 2,

and an outer casing 3 is installed in the well above the first gas-sandI. A line of tubing 5 is run downward through the casing 3 and bore 8 ofthe well and terminates in a perforate footer 50, 45 through which gasyielded by the sand 2 enters the bottom of the tubing and streams upwardto the top of the well. The gas delivered by sand I flows upward betweenthe tubing 5 and casing 3. 'I'he tubing 5 provides an inner passage, and50 the region between such tubing and the wall of bore 8 (and casing 3)provides an outer passage for conducting gas from the two strata I and 2to the top of the well. A header 4 of usual sort is provided at themouth of the well, and a pipe 55 connection, subject to a valve 9, ismade to a convenient receiver or pipe line (not shown).

The vertical interval between the two gasyielding strata I and 2 will befound to vary in different fields, and in this case two hundred and 60fty feet is given as exemplary. In the course of operation of the wellwater seeps from the sands I and 2 (and usually from other subterraneanstrata through which the well extends) into the bore of the well, and,as has been above indicated, 65 my invention consists in a procedurewhereby the normal tendency of such water to reduce the yield of thewell is eliminated or effectively minimized.

I install in the well a. removable packer 1, a

well-known device serving in known way to plug 70 the outer passage ofthe Well while leaving the passage within tubing 5 unconstricted.Removability of the packer is desirable, to the extent that it permitsthe withdrawal of the tubing 5 and the drilling of the well to lowerdepths, when 75 the yield of the sands I and 2 falls off. In a0-cordance with the invention, the packer 1 is installed and interval cabove the sand 2, and an interval a-i-b below the sand I. A portedcoupling 40, having its ports I4 normally closed, is installed in theline of tubing 5 an interval b above the packer. During the normaloperation of the well, the water. seeping in relatively small quantitiesfrom the sand 2 is collected in the bottom of the Well, and ordinarilythe pool of water rising in the bottom of the well will require from onetothree weeks to reach such level as to throttle the yield of the sand2. When such yield does become so throttled, a bailer is lowered throughthe tubing 5 and the collected wate'r removed in the usual way. TheWater seeping in relatively large quantities from the upper sand I (andfrom other water-bearing strata) drains into the bore of the wellbeneath the sand I and above the packer 1, while the gas yielded freelyflows upward between tubing 5 and casing 3. It will be perceived,therefore, that the bore of the well above the packer 'I and beneathsand I com- .prises a reservoir for the seepage water, and that theeffective depth of such reservoir is the interval between the ports I4of the coupling and the bottom of upper sand I4.

The seepage reservoir has a relatively great volumetric capacity. In thegiven case the interval a equals 150 feet, b equals 50 feet, and thebore 8 of the well is eight inches in diameter. Accordingly, thereservoir is of over 50 cubic feet effective capacity. Starting with thereservoir empty, the well may be operated from one to four or more weeks(depending on the rate of seepage) before the pool rising in thereservoir reaches the bottom of the sand, I. When the water reaches thesand I, or before it does so, the normal operation of the Well isinterrupted, and, in a manner presently to be described, the ports I4lying relatively close to the bottom of the reservoir are opened, andthe collected Water is drained into the tubing 5, whence' it may collectat the bottom of the well and be removed by bailing, or, to greateradvantage, may be blown out of the well in the manner already alludedto. In eithervcase the water is readily removed from the reservoir, andthe well restored to normal operation. It will be perceived that byvirtue of this method I can operate the well over relatively longintervals of time, without the sand I becoming flooded. Indeed, the sandI may be maintained in a drained, substantially dry condition. It willbe noted that the ports I4 are located an interval b above the packer.This interval (50 feet in this case) provides at the bottom of thereservoir adequate space for the accumulation of sediment and dirt,

which might otherwise plug the orifices I4.

It appears that the practice of my invention in one well of a fieldproves beneficial to adjacent wells. That is to say, I have found thatthe practice of my invention in one well operates to bring to life sandswhich were considered dead and non-yielding in adjacent Wells.

While many various provisions may be made for draining the water fromthe bottom of the reservoir into the tubing 5, an expansible coupling isparticularly desirable. Turning to Fig. II, the expansible coupling 40is shown in detail. It will be seen that the tubing 5 is parted at thecoupling, the coupling consisting of a cylinder portion 4I secured tothe lower end of the upper section of tubing 5, and a tubular portion 42secured by a union 43 to the upper end of the lower section of tubing 5.The portion 42 includes a hollow plunger 44 extending upward from ashoulder 45 and into the cylinder portion 4I. In normal operation of thewell, the lower edge of the cylinder portion 4I is seated upon theshoulder 45, and the tubular portion 44 extends upward into the cylinderportion and closes the ports I4 from within. When it is desired to drainthe water from the reservoir into the tubing 5, the usual ilangedconnection I of the tubing 5 with the header 4 is released, and theupper section of tubing is elevated, so that the cylinder portion 4I israised to the position shown in Fig. II. Thus, the ports I4 are opened,and the water collected in the reservoir drains into the tubing 5.

An expansible coupling I0 of modied and highly specialized structure isshown in Fig. III. Such coupling includes a head II which is secured inthreaded union I2 to the lower end of the upper portion of the tubingthat reaches from the coupling to the mouth of the well. The externalwall of the head II is provided with circumferential serrations or sliprings IIa, whereby the coupling may be grappled with fishing tools incase it be lost in the well. The head I I carries a cylinder portion I3which includes a circuinferen'tially extending line of relatively sinallorifices I4, and, within the cylinder portion I3, a plunger I5 isorganized. The plunger is formed with an annular shoulder I5a, and akeeper I6 secured in the lower end of the cylinder portion I3 serves, incooperation with such shoulder, to secure the parts in assembly;

from within the cylinder portion I3, the plunger continues downward in atubular extension I5b which is connected, by a union I'I, to the upperend of the lower portion of tubing 5 that extends from union I1 to thebottom of the well. As the drawing indicates, the head II and plunger I5are hollow, providing in conjunction with the tubing 5 a continuouspassage from the bottom of the well to the top-a passage which normallyis sealed from and independent of the outer passage (8) within which itextends.

Within the cylinder portion I3, the head II of the coupling is providedwith an upwardly and inwardly tapering seat IIb, and, advantageously,the seat is provided in an inset block I Ic. The plunger I5 is formed ofa relatively noncorrosion metal, such as brass or bronze, and the blockI Ic is formed of a cuprous, nickel alloy, such as is commonly known asMonel metal. Otherwise, the coupling may be formed of cast iron orsteel. plunger I5 is conical, providing a tapered face I5c adaptednormally to engage the seat IIb,

and, when such normal condition prevails, the.

body of the plunger closes the orifices I4 from within. In the alternateor unseated position of the plunger, the ports I4 are uncovered.

In normal operation the lower end of the tubing 5 rests upon the bottomof the w-ell, and, subject to the weight of the tubing. 5 above, thehead II of the coupling bears in seated position uponv the upper,tapered end of thev plunger I5. And if gas pressure exceeds the weightof tubing, the usual procedure is followed of using anchor rods andclamps.

'I'he upper or inner end ofthe When the reservoir is to be drained, theoutlet of the tubing 5 is vented to the atmosphere, or

into a low pressure receiver, and gas is permitted to stream violentlyupward through the tubing from the second sand 2. Then the upper sectionof tubing 5 is elevated, whereby the seat IIb is moved away from theface I5c of the plunger and the ports I4 opened, as shown in Fig. III.It will be observed that a region R is thus provided between the seatIIb and face I5c. -Thls region R. comprises a passage which is inclinedupward, toward the course of gaseous flow within the tubing 5, wherebythe gas streaming upward through the coupling produces a substantialaspirating effect. The orifices I4 are relatively small, so that waterdraining from the reservoir squirts in relatively fine streams into theregion R. Due to the relatively small orifices and the aspirating eiect,the liquid spurtinginto the coupling is broken up into small globuleswhich are ly drained from the reservoir and removed from I the well.

It has been found that the inwardly spurting liquid, in washing over thetapered surface I 5c of the plunger and the tapered surface IIb of theblock IIc, serves to cleanse the surfaces of such dirt and grit asnormally tend to collect thereon, whereby, when ythe upper section oftubing is again lowered, to close the orifices I4, a snug engagement ofthe surfacesillb, I5c) is insured.

I have found in a practical installation that, when the outer casing 3comprises six inch pipe and the inner tubing 5 comprises two inch pipe,the orifices I4 may be four in number, and each may be T95 of an inch indiameter.

What I claim as my invention is:

In the operation of a gas-well which includes an outer passage extendingdownward into communication with a subterranean gas-yielding stratum,and an inner passage extending downward into communication with a lowergas-'yielding stratum, the herein described method which includesnormally drawing off gas from said lower stratum and conducting itupward through said inner passage, drawing off gas and water from saidupper stratum and causing such gas to flow upward and said water todrain downward in said outer passage, to a level below the upperstratum, collecti-ng such water in a reservoir extending downward insaid well a Arelatively great distance below said upper stratum andseparated from said lower stratum, occasionally interrupting such normaloperation, and, by establishing ilow between said reservoir and saidinner passage at a point substantially below said upper stratum,emptying said reservoir, removing from the well the water emptied fromsaid reservoir, and thereafter restoring the well to normal operation,whereby said upper stratum ls maintained in substantially dry condition.

